Drill jig



F. MCCULLOUGH DRILL JIG Filed oct 9, 1944 www y April 1, 1947.

atented pr. 1, 1947 i UNITED STATES PATENT OFFICE DRILL JIG Frank McCullough, Detroit, Mich.

Application October 9, 1944, Serial No. 557,799 3 Claims. (Cl. 'J7-62) This invention relates to a drill jig.

It is the object of this invention to produce a jig for holding work pieces to be drilled which is simple in structure, eicient in operation, and which is capable of holding and locating many different parts having many different contours so that they will be drilled accurately.

My invention contemplates a drill xture which is separate from the drill so that it can be used right side up or positioned on its side while drilling, dependent upon the nature of the hole to be drilled. My drill iixture is also suitable for machine repair men or maintenance where accurate hand drilling is necessary.

My drill jig is also admirably adapted for accurately drilling completely through the diameters of such parts as balls and rings which have quite different contours.

Fig. 1 is a side elevation showing my drill jig.

Fig. 2 is a front elevation of the same.

Fig. 3 is a partial side elevation showing the work in position.

Fig. 4 is a section along the line 4-4 of Fig. l.

Fig. 5 is a section along the line 5-5 of Fig. 4.

My fixture comprises a base I having an integral upright post 2. The base I is provided with a V shaped seat 3 for the work which serves as the stationary jaw of the fixture. Movable jaw 4 is slidably mounted on the post 2. A screw 5 is journalled at its upper end in post I2 as at 6 and at its lower end in bearing 1 within base I. The screw has a threaded t with nut 8 which has a nice sliding lit within the guideway 9 of post 2. The jaw 4 has a nice machine sliding fit on post 2.

The drive between nut 8 and jaw 4 is effected through a shear pin I of a soft or shearable material such as brass. Nut 8 is provided with a hole II and jaw 4 is provided with a hole I2. The shear pin I0 has a tight fit in openings I I and I2 so that there will be no lost motion or play between driving nut 8 and the jaw 4. Pin Ill, however, is removable from openings II and `I2. Screw is provided with a socket I3 at its upper end for an Allen wrench by means of which screw 5 can be turned to raise or lower jaw 4. The object of the shear pin I0 is that of preventing the operator from turning the jaw 4 down on the work with such force as to damage either the work or the lixture, and in particular to prevent the operator from stripping the thread on screw 5 or in the internally threaded nut 8 or screws I5 or I9.

The jaw 4 is retained' on post 2 by means of a removable plate I4 which is secured in place by four Allen screws I5. When plate I4 ls removed I from jaw 4, jaw 4 can be slid oi of post 2 by movement toward the left, Figs.' 1 and 4, which disengages shear pin I0 from one or the other of openings II and I2 so that the shear pin I0 can be replaced whenever desired, and particularly when it has been sheared oli due to overloading of the screw 5. The drill jig is arranged to accommodate drills of different diameters. Accordingly jaw 4 is provided with a large opening I6 which is arranged to receive a headed bushing Il which serves as a guide for the drill I 8.`

Each xture will be provided with a plurality of bushings Il al1 having the same outer diameter but having different internal diameters. The size bushing I'I which will be mounted in opening I6 in jaw 4 will depend upon the diameter of the drill I8 which is to be used in the drilling operation. Bushings lI are retained in position in opening I6 by means of an 'Allen screw I9 which screws into a threaded bore 20 in jaw 4, Fig. 5. The shoulder 2| of bushing I'I is relieved as at 22 to receive the head of the Allen screwV I9. Bushing Il has a nice sliding fit in opening I6.

The base I is provided with a bore 23 which is centered or accurately aligned with bore I6 in jaw 4.

In use the jaw 4 will be elevated so that the work can be positioned in the V groove 3 by moving the work in from the left hand side of the xture, as shown in Fig. l, or by moving the work in to the groove 3 in a direction parallel to the longitudinal axis of the groove. After the size of the bushing I'I has been selected to conform to the diameter of the drill I8, the bushing is slipped into opening I6 and secured in place by the Allen cap screw I9. Therafter the jaw 4 is turned down. The lower face 25 of bushing I'I is accu- I ratcly machined so that it is located in a plane the hole is drilled completely through the dil ameter of ring 26. If the work piece is a vball or sphere, such as shown at 21 in Fig. 2, it will be seen that the bushing I'I will make a circular contact with the top of the ball 2l and the ball willl make a two-point contact with the V seat I3 so as to accurately position the ball in the xture and insure drilling accurately through the full diameter of the sphere. If the work piece is a rectangular sided block 2S, the at face 25 of the bushing will contact the upper face of the block 28 and the two lower corners of the block will make line contacts with the seat 3 so that as the jaw 4 isturned down the block 28 will be clamped in place and positively located so that the drill will bore a hole in or through block 28 perpendicular to, and centrally of, its upper face.

When a work piece, such, for example, as a ring 26, is drilled by hand, the workman will drill through the top bushing l1 to drill the hole in the top of ring 26 and will then drill upwardly through opening 23 to drill a hole in the bottom of. the ring. A bushing such as bushing l? will, of course, be used in opening 23 to guidethe drill. This manner of drilling will assure alignment of the holes in the top and bottom of work piece 26'; If the cylinder 26 were drilled completely through the top and bottom by hand drilling through the top bushing l1- onlythenA thefbottomhole; would most likely be out of line, with the topdrilled' hole because of the inability to maintain the alignment during hand drilling.

`Thus it will be seenfrom the aboveithat I'have produced a drill Xture that clamps the Work above and completely around the hole to be drilled and that is capable of automatically locating and centering workv pieces. of all general types, including ball s,vso that they will be drilled accurately; It isalsoevid'ent that I have produced a drill. fixtureV which, owing to the shear pin connection between thescrew drivey and the mo-vable jaw; will n otA injure the work due to anY excess clamping pressure andir which will not, for the same reason', damagejtjhe' fixture itself.

My drill xture is also' high lyuseful for accurate drilling where thework piece. has to be drilled from opposite sides for any reason.

1; A drill jigv comprising a. jaw having a seat for' the work to be'drill'ed; a post, a second jaw slidable along saidpost, a screw journalled insaid p,ostav nutslidable in saidpost having a threaded engagement with said screw, and a shearable drivingconnection' between'the nutand the movable jaw whereby when the xture is overloaded the connection will shear and-'thereby avoid injuryto the iixture or work.

2. The combination as set forth in claim 1 wherein the shearable-y connection comprises a shear' pin located in adjoining openings in the drivingnut andthe driven jaw.-

3. A drill jig comprising relatively movable jaws, one of said jaws having a V shaped seat for the work to be drilled, the other of said jaws having an opening therethrough opposite and centered 5 With respect to said seat, a drill guide bushing positioned in said opening and having an end projecting beyond the jaw, said end having a plane face perpendicular to the axis of said bushing, the said plane face of the bushing:` adapted to co- 10 operate withfsaid seat in clamping and positively locating the work when the jaws are moved relatively toward each other with the work therebetween, a post xed to one of said jaws and the other of said jaws beingslidable along said post, 115; screwymeans for sliding said jaw along said post and for clamping. the work between said bushing and V seat, the said jaw having the V seat being provided; with an opening therethrough axially aligned with the opening in the other jaw, the 20 opening in the work seat jaw also bengadapted to receive a drill girizleiloushing.l 'Y M FRANK MCCULLQUGH,

BEFEREN CES CITED The following references-are of record; i313 the le of this patent:`

UNITED STATES PATENTS OTHER REFERENCES 

